Apparatus for polishing sheets



April 1940. D. D. JOHNSTON 2,199,135

' APPARATUS FOR POLISHING SHEETS Filed D60. 21, 1936 IN VEN TOR. DW/GHT .0. JOHN5T HA5 A TTORNEYS.

Patented Apr. 30, 1940 UNITED STATES PATENT OFFICE 4 Claims.

This invention relates to an apparatus for pollaid on a carrier or waster sheet W and both ishing sheets, and particularly those sheets which are made of rather expensive metals, although not limited thereto.

In the past, considerable difllculty has been experienced in uniformly polishing the entire width of relatively thin sheets. It is among the objects of the present invention to overcome this difliculty.

Another object is to provide an inexpensive and eflicient apparatus for uniformly polishing the entire width of sheets, regardless of variations in thickness.

The foregoing and other objects will be apparent after referring to the drawing, in which:

Figure 1 is an elevation, .partly in section, of the device of the present invention.

Figure 2 is a sectional view on the line 11-11 of Figure 1.

Referring more particularly to the drawing, the numeral l2 designates a pair of opposed bearings in which there are'mounted the opposite ends of a rotatable shaft l3 driven in any suitable manner (not shown). Mounted on the shaft I3 are a plurality of closely abutting assembled rollsections H, the peripheries of which are coated with a suitable abradant. These assembled rollsections l4 constitute a polishing roll which is generally designated at A.

Immediately below and axially parallel the roll A is a cylindrical billy" roll B having reduced end portions it which rotate in suitable bearings l1 and H. The lowermost outer portions of the bearings i1 and are secured to individual vertical shafts I8 and I8, respectively. The lower' ends of these shafts carry diaphragmsfl and I9, respectively. These diaphragms l9 and I9 form part of a pair of conventional dash-pots, the

latter being designated at 2| and 2 I, respectively.

The bearings l1 and II are held against horizontal movement by side guides 22 which permit the roll B to be vertically reciprocated'upon operation of the dash-pots 2| and 2|.

-In order to raise the billy roll B into contact with the polishing roll A, fluid under pressure is supplied to the dash-pots 2| and 2|. This fluid pressure is obtained from a suitable source through a fluid line 25, which contains a constant pressure regulator 26. This regulator 26 supplies the fluid to a reservetank 21 and thence to the dash-pots 2| and 2| by lines 28, 29 and 30. According to the foregoing construction and arrangementof elements, the fluid pressure to thedash-pots 2| and 2| will be equalized.

.In operatiom a thin sheet 8 to be polished is are fed in any convenient manner between the rolls A and B,'whereupon the upper side of the sheet S is polished by the polishing roll A. Both ends of the billy? roll B are equally raised by the 5 diaphragms i9 and I9, thus raising it and the sheets W and S. In this manner the sheet S is made to firmly contact the polishing roll A under a constantly uniform pressure across the entire width thereof.

It'frequently happens that the sheet S is of uneven thickness. For example, let it be assumed that the left-hand side of the sheet S of Figure 1 is considerably thicker than the righthand side thereof. Under these circumstances 15 the billyrolls of the prior art yield downwardly at the point where the sheet is heaviest, but because of their construction and arrangement are also caused to move upwardly an equal amount I at their opposite ends, thus badly burning the 20 sheet and possibly also warping it.

According to the teachings of the present invention, this condition is eliminated, as the billy roll B moves'downwardly at the point where the excessive metal is present without any 35 other portion of the roll (such as the opposite end thereof) moving upwardly an equal amount. Thus, when the left-hand side of the billy roll B is downwardly displaced by the excess thickness of metal, it causes the bearing shaft ll 30 and diaphragm l9 to also move downwardly a like amount, as indicated by the dotted lines in Figure 1. This action builds up abnormal fluid pressure in the lines 28 and 30, which is relieved by a bleeder 32 located in the reserve tank 21 when excess pressure is in either dash-pot. As soon as the excess metal has passed from between the rolls A and B, the pressure momentarily drops due to the loss of that volume of fluid which has been bled, but the constant pressure regulator 26 immediately opens and builds up once more the predetermined pressure, thus bringing both ends of the billy roll B to equal positions and pressure with relation to the abrading roll A.

It is obvious that shouldthe heavy portion of the sheet S be present on the right-hand side of Figure 1, the bearing ll, shaft I8 and diaphragm It would move downwardly without efiecting any substantial vertical movement of v the left-hand side of the billy roll B. Should the heavy portion of the sheet S occur in the middle thereof, both ends of the billy" roll 3 would move downwardly an equal amount, while heavy portions between the very center and one edge of the sheet would divide the movement between the two floating ends in proportion.

While I have shown and described one speciflc embodiment of my invention, it will be understood that I do not wish to be limited exactly thereto, since various modifications may be made without departing from the scope of my invention, as defined by the following claims.

I claim:

1. Apparatus for polishing sheets and the like comprising, in combination, a power-driven rotatable polishing roll, an abrading medium carried by said polishing roll, an idle rotatable pressure roll disposed opposite and adjacent said polishing roll, separate fluid means for applying pressure to each of the ends of said pressure roll to influence the same towards said polishing roll, means for supplying fluid at constant pressure to each of said fluid means, and means for relieving excess fluid pressure in either of said fluid means without substantially varying the fluid pressure in the other of said fluid means.

2. Apparatus for polishing sheets-and the like comprising, in combination, a power-driven rotatable polishing roll, an abrading medium carried by said polishing roll, an idle rotatable pressure roll disposed opposite and adjacent said polishing roll, separate fluid means for applying pressure to each of the ends of said pressure roll to influence the same towards said polishing roll, common means for supplying fluid at constant pressure to each of said fluid means, and means for relieving excess fluid pressure in either of said fluid means without substantially varying the fluid pressure in the other of said fluid means.

3. Apparatus for polishing sheets and the like comprising, in combination, a power-driven rotatable polishing roll, an abrading medium carried by said polishing roll, an idle rotatable pressure roll disposed opposite, and adjacent said polishing roll, separate fluid means for applying pressure to each of the ,ends of said pressure roll to influence the same towards said polishing roll, means for supplying fluid at constant pressure to each of said fluid means, and common means for relieving excess fluid pressure in either of said fluid means without substantially varying the fluid pressure in the other of said fluid means.

4. Apparatus for polishing sheets and the like comprising, in combination, a power-driven rotatable polishing roll, an abrading medium carried by said polishing roll, an idle rotatable pressure roll disposed opposite and adjacent said polishing roll, separate fluid means for applying pressure to each of the ends of said pressure roll to influence the same towards said polishing roll, common means ,for supplying fluid at constant pressure to each of said fluid means, and common means for relieving excess fluid pressure in either of said fluid means without substantially varying the fluid pressure in the other of said fluid means.

DWIGHT n. JOHNSTON. 

